Coordinated stimulation of axon regenerative and neurodegenerative transcriptional programs by Atf4 following optic nerve injury

To understand the contributions of the Integrated Stress Response (ISR) to the axon regenerative and neurodegenerative transcriptional programs activated by axon injury in the CNS, we evaluated by RNA-seq the retinal transcriptomes of conditional knockout mouse lines for components of the ISR three days after optic nerve crush injury. Prior to injury, intravitreal injection of AAV2-mTagBFP2-ires-Cre under the control of the human synapsin-1 promoter facilitated neuron-specific knockout of Eif2ak3, the gene that encodes the ER stress-responsive kinase Perk; Atf4, the gene that encodes the ISR mediator Activating transcription factor-4; or Ddit3, the gene that encodes another transcription factor that can mediate the ISR, C/ebp homologous protein, or CHOP. We compared the expression profiles of these transgenic retinas after injury to retinas from wildtype mice with and without injury to identify transcripts whose regulation by axon injury is dependent on ISR signaling. Overall design: Comparative gene expression analysis of whole mouse retina 3 days post-optic nerve crush (3 dpc) across three transgenic lines (ATF4 cKO, PERK cKO, and CHOP cKO, n=4-5 per genotype) compared to similarly treated wildtype retinas (n=5), with uninjured wildtype (n=4) serving as an additional control.